A very unusual dry docking at Fleet Maintenance Facility

YOM252Docking

Lt(N) Peter Summers and Ashley Evans
FMF CB
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As those on-site at Fleet Maintenance Facility Cape Breton (FMF CB) have likely noticed, there are currently three vessels – the 250 Barge and two Camel Fender Barges – docked in the dry dock, a big difference from the usual sight of one, or none.

Although unusual, this is not the first time three vessels have been docked there. Records show this was fairly routine through the 1960s to 1980s, and was normally a combination of the small minesweepers (Bay class), gate vessels (Porte class), and various auxiliary vessels and barges.

The last three-vessel docking appears to have been Oct. 31, 1985, when HMCS Fundy, HMCS Miramichi, and YDG 3 were docked together.

There was one instance of a four-vessel docking, on Jan. 13, 1971, with HMCS Beaver (ex YSF 216), YMG 189, YMG 190, and YC 428 all docked together.

The last time YOM 252 (250 Barge) was docked at FMF CB was May 17,1993, but since then it has always gone to contractor yards for routine docking.

What are these barges used for?

YOM 252 is an environmental barge. It contains a number of tanks that receive liquids from ships that pump out their tanks or bilges to the barge. The barge then takes the liquid away to be properly discharged at a processing or storage facility.

This is very useful as it enables ships to offload liquids as part of their work periods without having to go over to the Colwood side of the base.

Camel Fender Barges are used for berthing U.S. Navy submarines. The barges have underwater structures that hang down about six metres (20 feet) below the waterline. One side has horizontal rubber fenders that press against the columns of a pier or jetty, while the other side has vertical rubber fenders that the submarine’s hull will press against. This permits submarines to be tied up to jetties that are designed for surface ships and would otherwise be too tall, causing the submarine to bump against the jetty columns.

Docking Plan for the three vessels

The docking plan is a drawing that shows the dock blocks the vessel sits on within the dry dock. The Naval Architecture section is responsible for producing all docking procedures and specifications, as well as providing oversight for docking evolutions.

There were four people from Naval Architecture involved in the docking planning process: the Docking Officer and Assistant Docking Officer who developed all of the plans; a Structural Engineer who assisted with analyzing the strength of the Camel Barges and the suitability of various block layouts; and an Engineering Design Technologist who produced (and constantly updated) the drawings for the docking plan.

The Docking Officer works closely with the Dock Master and the Project Leader to plan the docking evolution and coordinate the support required. This includes where the vessels will be located in the dock, how they will be supported, tug support, diver support, production support, environmental and safety considerations, working with Industrial Engineering, and other stakeholders.

All docking plans begin with a set of calculations that check a variety of factors such as adequate blocks to support the vessel weight, enough support to prevent the vessel from overturning due to high winds or an earthquake, that the vessel will land in a controlled manner that doesn’t damage the keel, and that the vessel will remain stable once the water is removed.

Docking YOM 252 Barge

The docking plan for the YOM 252 Barge was relatively simple due to the barge having a wide, flat bottom. A partial docking plan existed from a previous Docking Officer, so making the plan was mostly a matter of confirming the blocking would have adequate strength and stability to hold up the barge, and choosing a location in the dock.

Some difficulty arose due to the YOM barge size – it has a width of more than 18 metres (60 feet) and the clear width at the entrance of the dock is a little less than 19 metres (65 feet).

Additionally, because of its width, the barge needed to be placed on very tall blocks (two metres or 6.5ft) so it wouldn’t contact the stepped walls of the dry dock. Further complicating the issue, two sections of vertical piping within the dry dock had to be removed on short notice by Industrial Engineering so they were not crushed when YOM was brought in.

Docking Camel Fender Barges

The docking plan for the Camel Fender Barges was much more complicated as Naval Architecture did not have the official drawings for the Camels. These barges are on loan to Maritime Forces Pacific from the USN as part of a memorandum of understanding where the Royal Canadian Navy keeps and maintains the barges so USN submarines can berth in Esquimalt.

Therefore, the official drawings do not exist in any DND database. Naval Architecture had some drawings they suspected (correctly) did not match the actual design of the Camels, so a dive survey was conducted to verify the structure.

Due to low visibility in Esquimalt Harbour water, and due to the positioning of the Camels, it was difficult to produce accurate drawings of the underwater structure.

In the end, FMF CB was supported by a number of separate dives by Fleet Diving Unit (FDU (P)) and by a contractor with live video/communication capability.

Due to the compressed schedule, by the time the drawings could be produced with confidence, the dock blocks were already being put in place. This in turn led to late updates to the docking plan and changes to the dock blocks that had already been put in place.

Unfortunately, this dive also found on one of the Camels, two of the 10 legs that would support the barge in the dry dock were extremely bent and could not be used. It’s unclear how the legs, which are made of large steel I-beams, were damaged. However, the bent legs required Naval Architecture staff to confirm the clearance on the dock blocks to see if the legs would interfere with them while the dock was being pumped down.

From the information they had, it appeared this would be okay. They also added extra blocks to the docking plan to provide added support in case any of the blocks were knocked over by the bent legs.

Lt(N) Peter Summers, Deputy Naval Architecture Officer said the most rewarding part of this process was demonstrating FMF’s capability.

“We had a significant challenge trying to dock the Camels with their unique underwater structure and so many unknowns about what it actually looked like. To further complicate things, we then added the YOM to the docking plan on short notice.”

Despite all of this, everyone involved worked extremely hard to overcome these challenges and make the docking a success. I suspect it would be very difficult to contract out a docking of that nature on a short timeline and find anyone willing to take on the challenge, so I am very proud of what FMF was able to accomplish.”

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Filed Under: Top Stories

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